In general, the logging climate has changed in the past several decades, in that logging regulations and protocol have mandated taking more of the logs out of the logged portions out of the woods. For example, in years past, loggers would not bother with anything under 12–16 inches, whereby only the larger, old-growth timber was taken out of the forest and used for industrial processing for a variety of wood-related products. However, the climate has drastically changed whereby now every aspect of the logs which can reasonably economically be removed are taken from logging sites. Therefore, in essence, at the time of this invention, any log which can be properly de-limbed and economically removed is removed from the site. This changes the dynamics of log removal from the logging area, whereby many of the smaller trees (as well as the larger ones) must be removed from the logging area and taken to a central landing area for immediate processing or otherwise referred to as “manufacturing” in logging vernacular.
Therefore, to meet the demands of the present logging operations, it is desirable to have an apparatus which can operate in a logging job and which can accommodate the wide variety of logs which is required to be extracted, and further which can be adapted to cover a very large radius and have the ability to extend over a great range to extract logs to a central landing area for manufacturing. Further, this generally requires powered actuators and a mobility system to accommodate these high demands. In addition to the technical requirements and the new logging environment for which logging operations now exist, there are additional considerations of increasing the safety for loggers who are oftentimes injured or “busted up” in the field. It is therefore desirable to have a unit which can execute the job of extracting the logs from the logging area to a central area without putting many loggers in harm's way by setting chokers or having to be near the unit for operation. In addition, an apparatus which can be retrofitted to any number of cable topographies, is particularly advantageous. As described herein below, the various prior art devices lack the versatility to be implemented in a variety of cabling arrangements which are described in the figures below.
The teachings of U.S. Pat. No. 5,653,350 (Maki) discloses a grapple carriage which is essentially only suitable for a “skyline” cable arrangement. In general, a unit such as this is fairly large and heavy, and can weigh thousands of pounds and the weight would be in excess to use any other method than the skyline cable topography.
The other prior art references, such as Hale U.S. Pat. No. 3,647,225, and Mitchell U.S. Pat. No. 3,540,770, are units which are particularly conducive for very large logs such as old growth timber. The jaws, which essentially are non-actuated or have very limited actuating ability, are primarily fed by the gravity of the unit. This is not reliable for smaller logs or, in particular, bundles of logs where you need actuating jaw clamps to contain those logs as a unit for haul back.